Automatic current regulating device



2 Sheets-Sheet l 0M Pkt-QAM@ Dec. 27, 1932.

TTORNEY "1'" "VVV VVV" INVENTOR GASTEN ADELIN MATHIEU BY AAAAAAAA 2 Sheets-Sheet 2 G. A. MATHIEU AUTOMATIC CURRENT REGULATING DEVICE Filed De() 14, 1927 Dec. 27, 1932.

Patented Dec. 27, 1932 uNi'FpED STATES PATE-NT oli-rice GASTON ADELIN MATHIEU, OF LONDON, ENGLAND, ASSIGNOR TO RADIO CORPORATION v 0F AMERICA, A CORPORATION OF DELAWWARE AUTOMATIC CURRENT REGULATING DEVICE Application iledrDecember S14, 1927,*S-era1kNo.

This invention relatesv to automatic limiting and Aregulating devices, foruse in electrical signalling, and While rnot confinedto applicedionl thereto,is especially suitable for l limiting or regulating the intensity oi signals transmitted over a land line from' the output side of a wireless or other telephone or telegraph receiver,

In cases in Which'signals received by radio tel'egraphy or telephony are amplified and then re-transmittedover a `land line or the like,v considerable `diiiiculty is experienced especially when using short wavesvfor instance inthe case of telephony, owing to the large fluctuations liable tooccur'in the intensity ofreceived signals, For example, the amplitude of the low ,frequency component l of speech signals at the output end of an amplifier associated with La. wireless receiver, may vary between ll, and 50 milliamperes, and it willlreadilybe appreciated'tliat so rlarge a variation is very serious, sinceit may cause overloading of repeater' valvevin the land line and give rise to distortion in other ways. Moreover, such large variations are greatly in excess ofthe limits for commercial tele'phony y'Briefly the object of this invention is to provide a device which Will automatically rcontrol within definite limits' the signals to i beI transmitted.

l `Another 'obj ect of this invention is to provide an automatic limiting device which will be sensitive yand instantfin operation.

According to this invention anl automatic limiting and regulating device comprises signal intensity reducing means and means 4controlled by the intensity of the signals to be limited, for Vvarying the attenuation or weakening properties of the said intensityreducing means.4 n y f; 1

- In one way of carrying `outthe invention,

as applied to a wireless receiver and amplifier re-transmitting signals over a land line, the

signals from the last stage ofthe wireless receiver which last stageinay, orinstance, comprise two valves 'in push-pull connection are amplified by meansof a low frequency amplifier and re-transini-tted ythrough an in- -terposed continua-tion orartifcial line over 239,843, and in Great Britain January 7, 1927ik a land line. This interposed line may conveniently comprisea plurality ofresi'stances in series parallel arrangement. i

Bridged across two points in the interposed line is a plurality of resistances in series and a plurality of high speed mechanical relays arel associated Withsaid resistances in suchv bv varying the amount of' resistance effec-` tively line. l

f The relays are arranged to be actuated by ydifferent amplitudes of current, and their yoperative windings are connected so as to be influenced by the intensity of signals in the output side of the wireless receiver. For

shunted across the said continuation example, the first relay may be adapted to be operated by a strength of l milliampere, the secondy by 3 milliainperes, the third by 5 milliamperes, and so on. f

In one arrangement of relays, each relay is provided with two windings, one a signal energized winding, and the other a vconstant supply winding. The latter kwindings are Vconnected in parallel across any convenient source of electrical energy, and, if desired, each winding may be connected in series With a regulating resistance whereby the sensitivity, speed of response, or setting of the associated relay may be adjusted.

`, IIhe signal energized windings are connected in series across the output side of a direct current ampliier, whose input lside is supplied from the last stage yof. the wireless receiver. It will be appreciated, therefore, that the amount of resistance in shunt across the interposed continuation or artificial linewill depend upon `the amplitude of the received The employment of an artificial line in the first modification herein described has the advantage that the relay contacts are substantially prevented from transmitting disturbance to the line.

Other advantages will become apparent from the following specification when read in connection with the drawings in which:

Figure 1 shows in schematic form a general arrangement for receiving signals by wireless and retransmitting them over a land line.

Figure 2 shows in diagrammatic form an attenuation network, such as that incorporated in the arrangement of Figure 1.

Figure 2a shows in detailed diagrammatic form one of the resistance units incorporated in the arrangement of Figure 2,

Figure 3 shows in diagrammatic form a relay arrangement for varying the attenuation properties of the network shown in Figure 2 in accordance with the strength of the received signals, and

Figure l shows in diagrammatic form an arrangement for supplying current for the control of the relays incorporated in the apparatus described with reference to Figure 3.

Referring to Figure 1, A is an aerial associated with R, a supersonic heterodyne receiver (any other suitable kind of radio receiver may, of course, be employed), followed by RF, a high frequency amplifier which in turn feeds DS a detector separator adapted to separate the direct current component of rectilied high frequency current from the low frequency alternating current caused by ydemodulation. The apparatus constituting the detector separator will be described in further detail later.

The low frequency alternating current output from the detector separator is fed through an attenuation network RN, thence through a low frequency amplifier AF if desired, to a land line (not shown). The direct current output from the detector separator is passed through a. direct current amplifier DCA to actuate a series of controlling relays at CR adapted to vary the attenuation constants of the network RN.

The relays at CR are connected in series and arranged to be actuated one after another with increasing values of direct current fed to them, the successive actuation of the relays serving to vary step-by-step the attenuation constants ot the network RN. It will be seen that the strength of current actually fed to the relays will be. proportional to the amplitude of the received carrier wave, and` assuming that this amplitude varies proportionally with the amplitude of the low frequency alternating current output from the detector separator as will generally be the case, the apparatus can be so adjusted that the attenuation constants of the network RN will be varied in accordance with the amplitude of the signals supplied thereto.

Referring to Figure 2, which shows diagrammatically the relay apparatus indicated by RN in Figure 1, together' with the associated relay contacts, the network comprises a plurality (in this case six) of resistance units` 1, 1A', v2, QA; a, 3A; 4, 4A; 5, 5A; 6, 6A. Associated with each ,unitis s, pair of relay contacts S1,S7; Sp2, S8; S3, S9; and so on. Each pair of contact'sis associated with one of the relays at CR (Figure 1), the arrangement being such that when one of each pair of contacts is closed, the other of that pair is opened, and vice versa.

Preferably the resistance value of each of the resistance units incorporated in the network RN is readily adjustable.

Figure 2a shows an arrangement whereby this may be effected.

Referring to this figure, a resistance unit, for example, the unit 3, 3A of Figure 2, comprises three series resistances R1, R2, R3, and three parallel resistances RIA, R2A, and R3A, ytogether with switches S13, S14, S15 and S18. All the resistances are of equal value and it will be seen that by manipulating the switches S13, S14, S15, S16, S17, S18, the resistance value of the unit may be adj usted over a wide range.

Figure 3 shows the circuits associated with one of the control relays, say, the first relay. The other control relays are similarly arranged but are not illustrated for the sake of clearness in the diagram. The output from the direct current amplifier is passed to the main winding CW of the control rela and then through the main windings of al the other relays in series. The control relay is arranged to make or break a circuit passing from a main supply B, through an indicating lamp L, relay switch winding WR, Vcontrol relay contact CWl and control relay armature to earth. The relay switch winding VR actuates relay contacts S1, S7, associated with the resistance units 1, 1A (see also Figure 2).

For purposes of ready adjustment, each control relay is provided with a response adjustment winding, such as AClV, energized from a variable tapping upon a potentiometer P through a variable resistance VR. A limiting resistance LR is connected in series with the resistance VR and is bridged by a pair of normally closed relay contacts VRlS adapted to be opened by the winding WR when control relay CW is actuated. The resistance LR is necessary to the proper functioning of the apparatus and is of such value as to permit the control relay to close and open at substantially the same values of rising and falling current respectively. As is well known, the majority of relays having closed at a given value of current, will remain closed for a considerably less value of curr 3 is as follows:

rent. MAS is a double pole socket into which a milliameter MA maybe plugged to facilitate adjustment.

The operation of the device shewn inFig.`

lllhen the current in the f i l 'detector separator indicated at DS in Figwinding CW is not suiiicient to overpower the steady spacing current passing through the winding ACW, which current value can be regulated by means of both the potentiometer P, working 1n series with the lampL 1n any electrical main circuit available and they series resistance VR; the tongue of the arma'- .ture of the relay moves to the left and bears on Contact lCVV which lights the controlling lamp L1. No current passes in the winding WR of the auxiliary relay and in that posi-y tion contact VRlS and S1 are closed and rvcontactS `is open, thus removinr completely the attenuation line constituted by the resistance l and 1A from the main line circuit and short circuiting the resistance LR in the electrical biasing circuit to the winding ACWIT of the main relay. j

When the current flowing in the winding CW rises to a value suiiiciently high to overcome the antagonistic electrical and mechanicreases the electrical biasing current in the main 'relay circuit including winding AGVV by introducing in said circuit the resistance LR. The elements l and lAin the line limit the amplitude of the current sent out over the line.

To briefly repeat the operation of the limiting device VVhen the armature of the main relay is in center position with respect to coming in and being amplified and sent out over the line. The switches VRlS and S1 are in their upper position, i. e. closed because WR is not energized. The resistance LR is short circuited, likewise the limiting elements 1, 1A. Switch S7 is open. y

The same conditions prevail when the l armature of the relay is in contact with-the contact lW due to the fact that the current in yCW is below normal and the current in ACW drives the armature to the left. In the latter position alamp Ll is energized.

When they armature of the relay is in the right hand position due to theofact that the current in GWV is above normal ,and the field thereof overcomes the field of ACW, WR is energized and pullsdown the movable contacts of switches VR1S,S1, and S7. ,The

switches VRlS and S1 are open. LR is in series. with ACW and l, 1A is introduced intg the line by the closing ofS7 and opening 0f 1. l i l l 3 i y 1 Figure 4 shows in diagrammatic formthe" ure l. u

Referring to Figure 4, V1 is a thermionic valve which is adjusted by means of the grid bias batteryEb, to rectify and demodulate the signals. T2 Vis an output transformer, Cl abye-pass condenserdfor the high-frequency current; C2 and C3 are condensers. of

frequency current; Chl is a choke adaptedl to let pass direct current but to stop high'and is an anodevbattery.. i y j Although for the purpose of illustration` SI have fully shown and described the at present preferred form of *myv invention and theoperation thereof, it will be clearly'understood that I do not limit myself thereby except as marked out' in the following claims.

I claim: f l -1.,A'n automatic limiting and regulating device, suitable kfor use in signalling systems Land comprising signal vintensity reducing means, means forvarying the attenuation or weakening properties of the intensity'reduclng means comprising a plurality. of relays kenergized by currentssubstantiallyr proportional to the intensity of the ksignals to be limited and regulated and adapted to be actuated in succession by rising values of said intensity, so that theattenuation or weakening Vftuated. windings GW' and ACV normal current is 2. In apparatus for automatically limiting and regulating the amplitude of current over a signalling channel, the combination of an incoming line, signal detecting means connected thereto, an outgoing line, signal intensity reducing means, interposed between said detecting means and saidk outgoing line, said reducing means including a network comprising a plurality of resistance units, each unit including a plurality of resistances some of which are arranged to be connected in series with said outgoing line andothers of which are adapted to be connected in parallel with saidline, switching means connected `with said resistances and with said line,`and relay means connected with said switches and actuated by current from said detecting means to vary progressively the number of said resistances interposed in said line by said switches. f

-such size as to let pass both lhighandlow ylow frequency alternating current and lEA 3. An automatic amplitude limiting and regulating device to be used in signalling apparatus including, signalling receiving means followed by signalling detecting means, amplifying means, and signalling intensity reducing means, interposed between said detecting means and said amplifying means, means for varying the attenuation or weakening properties of the intensity reducing means including a plurality of relays, and means for diverting a direct current component from the output circuit of said detecting means to energize and actuate said relays progressively in accordance with the amplitude of the received signal.

4. In radio apparatus for automatic signal amplitude control, a signal transmission line. means associated therewith for receiving a signal, means for demodulating said signal, means or selecting a direct current component from the energy resulting from said demodulation comprising a path for the passage of the direct current component from the output of said demodulating means, and means in said path to prevent current at the signal frequency from flowing therein, a plurality of relays each including a winding connected with said path, said relays being adapted to be actuated by variations in the amplitude of said direct current component, a resistance net work arranged to be connected between the output circuit of said demodulating means and the outgoing line, and a plurality of switches associated with said resistances and actuated by said relay windings to alter the amount of resistance connected in said line.

GASTON ADELIN MATHIEU. 

